Indicolite: Blue Tourmaline.
Ingot: Metal cast into a bar or other shape.
Inlaid: Past tense of inlay.
Inlay: A decorative technique in which part of the surface of a piece of jewelry, furniture, or ceramic is cut away and stone, mother of pearl, or some other substance is imbedded into the hollowed-out area so that it is level with the surface of the piece. See also channel inlay.
Intaglio: Italian for "carving", an Intaglio is a carved gem wherein the design is engraved or carved into the object so that it sits below the surface plane of the material, as opposed to a cameo in which the design is raised from it's background, in relief. This technique was often used for seals, which made a raised impression in wax used to seal a letter or authenticate a document. It was commonly attached to watch fobs, since the watch fob is a good manner of carrying a seal. Once seals fell out of common use, the intaglio tended to face out to the viewer rather than down as on a seal. Some of the most commonly found Victorian intaglios were carved in carnelian, an orange-brown variety of chalcedony.
Iolite: (also called dichroite or water sapphire). A silicate of alumina, iron, and magnesia which is usually violet-blue, but can be deep blue, light blue-gray, and yellow-white. Makes a beautiful transparent gemstone which is remarkable for its dichroism.
Iridescent: A display of lustrous rainbow-like colors. The colors seen in an oil slick or mother of pearl are good examples of iridescence. Synonymous with "Pearlescent".
Iron: The most common metallic element which usually appears dark brown, from oxidation or impurity, but when pure is silvery-white. Iron is found abundantly in nature, usually in combined forms such as hematite, limonite, magnetite, and taconite. It is frequently alloyed in a wide range of important structural materials like cast iron, steel, and wrought iron. It is easily oxidized (rusted) by moisture, and is attacked by many corrosive agents.
Iron Pyrite: See Pyrite.
Irradiation: The process of bombarding a gemstone with X-rays, gamma rays or streams of subatomic particles in order to change the stone's color.
Ivoride: See French Ivory.
Ivorine: See French Ivory.
Ivorite: See French Ivory.
Ivory, French: See French Ivory.